One-way compression and starting release

ABSTRACT

A compression control device for a two cycle motorcycle type engine comprises a valve that has successive operating positions corresponding to (1) CLOSED for normal operation of the engine; (2) ADDED VOLUME for starting with a controlled reduced compression ratio; and (3) VENT for braking. The control device has a range of movement for non-critical determination of the operational mode.

United States Patent Harper et al.

ONE-WAY COMPRESSION AND STARTING RELEASE Inventors: Michael Ronald Harper, Cedarpines Park; Neil David Fergus, Crestline, both of Calif.

Victor Products, Inc., Hesperia, Calif.

Filed: Oct. 15, 1973 Appl. No.: 406,155

Assignee:

U.S. Cl. 123/48 D; 123/97 B; 123/182 Int. Cl. F011 13/08; F02d 15/04 Field of Search 123/182, 97 B, 48 D;

References Cited UNITED STATES PATENTS 1/1937 Loeffler 123/182 X Primary Examiner-Char1es .1. Myhre Assistant Examiner-W. Rutledge, Jr. Attorney, Agent, or Firm-Fiam & Flam [57] ABSTRACT A compression control device for a two cycle motorcycle type engine comprises a valve that has successive operating positions corresponding to (1) CLOSED for normal operation of the engine; (2) ADDED VOLUME for starting with a controlled reduced compression ratio; and (3) VENT for braking.

The control device has a range of movement for noncritical determination of the operational mode.

5 Claims, 3 Drawing Figures a0 4%. 55 Z, 7 48 I&

ONE-WAY COMPRESSION AND STARTING RELEASE FIELD OF INVENTION This invention relates to motorcycles, and particularly to the compression characteristics of the engine as they pertain to starting and braking.

BACKGROUND OF THE INVENTION At least two types of devices have been utilized in the past which tap into the compression chamber of a two cycle engine. One device is designed to release the pressure in order to gain braking power which may be necessary under severe conditions, such as under steep downhill conditions. Another device is designed to release the pressure when starting the engine so that less effort is required to carry the piston past its maximum compression position. The same device cannot be effectively used for both purposes without compromising the characteristics because the vent size for best braking is far larger than vent size for best starting. Some sort of selectively shiftable throttle device would seem to be an obvious solution. However, certain problems are encountered with starting compression releases. Particularly, there is a danger of fouling the spark plug. Starting requires that the fuel be compressed to a certain degree; with a vent, critical compression will not occur unless the kick is sufficiently rapid. Thus with weak kicks on the starting lever, fuel is repeatedly forced into the chamber. To prevent plug fouling and flooding, it is important to achieve starting the first or second time.

The primary object of th is invention is to provide a new starting mechanism for any kick start engine, and one particularly useful in for combination with a compression braking release in two cycle engines.

SUMMARY OF THE INVENTION In order to achieve the foregoing objective, I provide a valve mechanism that has three successive positions that phase in as a function of displacement of the sliding member. The first position, to which the sliding member is biased, corresponds to closed. The second position corresponds to the addition of a predetermined fixed volume to the combustion chamber. The third position corresponds to venting for braking functions. The second and third positions take in a range of movement of the sliding member.

The addition of a fixed volume for purposes of starting achieves a controlled lower compression ratio that is achieved whether the kick lever is operated rapidly or (within limits) slowly. A start is more positively assured since a wider range of kick motions is yet operative to achieve the critical compression ratio adequate for starting. Nevertheless, the force required is reduced due to added volume. Furthermore, the fuel is trapped for explosion with the fuel in the main cylinder. Accordingly none of the fuel is wasted.

BRIEF DESCRIPTION OF THE DRAWINGS A detailed description of the invention will be made with reference to the accompanying drawings wherein like numerals designate corresponding parts in the several figures. These drawings, unless described as diagrammatic, or unless otherwise indicated, are to scale.

FIG. 1 is an axial sectional view of compression control mechanism incorporating the present invention,

the engine parts forming the cylinder being shown in phantom lines. In FIG. 1, the control mechanism is shown closed.

FIGS. 2 and 3 are views similar to FIG. 1, but showing the sliding member of the valve in second and third positions for starting and braking.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT The following detailed description is of the best presently comtemplated mode of carrying out the invention. This description is not to be taken in a limiting sense, but is made merely for the purpose of illustrating the general principles of the invention since the scope of the invention is the best defined by the appended claims.

Illustrated in phantom lines in FIG. 1 are engine castings forming a cylinder 10 in which a driving piston 12 is reciprocable. In the present instance, a spark plug 14 is located on the top of the cylinder for timed ignition of the compressed fuel.

In order to modify the starting and braking characteristics of the engine, a compression control device 16 is provided. The device comprises a slide valve mechanism that includes a hollow valve body 18 attached to the engine parts. For this purpose, the body has an exteriorly threaded reduced extension 20 that fits a specially tapped hole 22 in the engine head. This hole is located adjacent the hole for the spark plug, and is accessible for attachment of the body 18 between the heat radiating fins 24.

The body 18 provides a chamber 26 that when open to the cylinder increases the effective volume thereof. For this purpose, there is provided a sliding valve member that extends axially of the body 18, chamber 26 and extension 20. The valve member includes an upper tubular part 30, and a lower stern part 32 fitted and secured to each other or formed in one piece. The valve member also includes a cap 34 fitted to the top of the tubular part 30. The tubular part 30 is slidably mounted in a guided aperture 35 of a plug 36 fitted into the upper end of the valve body 18. The lower ends of the stem 32 has a conical closure head 38 that seats on the edge of the extension 20. The stem 32 has substantial clearance relative to the extension 20 so that, when the stem 32 is moved downwardly, (FIG. 2) full communication is established between the cylinder and the chamber 26. In this position, the fit between the lower end of the tubular part 30 and the aperture 35 effectively seals the upper end of the chamber. Accordingly, modified compression characteristics of the engine are determined for starting purposes. Fuel captured in the chanber 26 is exploded along with the fuel in the cylinder, and the resulting explosive force acts upon the piston and is thus utilized.

The valve member 28 is operated manually, as by a cable 36 and hand lever (not shown). The cable 36 extends through a slot 38 in the cap with its lower end anchored to the body plug 36 as by a set screw 40. The cable is surrounded by a flexible sheath 42 that seats in a recess 44 at the top of the cap 34. Axial force exerted between the cable and the sheath at a place remote from the control device 16 causes a downward thrust to be imposed upon the cap 34 and companion parts of the valve member 28, causing closure head 38 to open the valve. A compression spring 46 interposed between the plug 36 and the cap 34 biases the valve member to the closed position of FIG. 1.

By moving the valve member 28 beyond the position of FIG. 2 and into the position of FIG. 3, the valve chamber 26 and the cylinder are vented. For this purpose, the tubular valve part 30 has side ports 48 that communicate with the chamber 26 at the lower end of the aperture 35 when the valve member is moved downwardly by a sufficient amount. The tubular member exhausts to atmosphere through its upper end. For this purpose, the cap 34 has intersecting axial and radial ports 50 and 52.

The dimensions of the vent openings are scaled so that the compression of the engine is effectively released, thereby achieving a braking assist when braking requirements are high.

The user of the motorcycle very quickly learns the proper feel of the operating cable to achieve alternate modes of operation. The engine produces characteristically different sounds in the normal running, starting and braking modes. The device is exceedingly simple, yet provides important and/or desirable operating features to the engine.

Intending to claim all novel, useful and unobvious features shown or described, we make the following claims:

1. In a compression control'device for use with a two cycle motorcycle engine having a hole leading to a cylinder:

a. a valve body providing a chamber of predetermined volume, said chamber having an inlet opening and a vent;

b. means for attaching said valve body to said engine to place said chamber inlet in registry with said engine hole; a

c. a valve member carried by said valve body and guided for movement in a defined path;

d. means forming a limit to the movement of the valve member in one direction in its path in which said valve member interrupts communication between the registered chamber inlet and engine hole;

e. spring means urging said valve member toward said limit; I

f. an actuator manually operable to move said valve member away from said limit a certain amount to establish communication between said engine hole and said chamber;

g. means operable between said valve member and said vent to open said vent only after a predetermined movement of said valve member farther away from said one limit than said certain amount whereby, for starting purposes, a definite sealed incremental volume is added to said engine cylinder, and whereby for braking purposes, said engine cylinder is vented.

4 2. The compression control device as set forth in claim 1 in which said valve body has a guiding aperture for said valve member-opening into said chamber; said valve member including a tubular part and a solid part fitted into the tubular part, the tubular part being guided at said aperture for substantially rectilinear movement and comprising passage means to said vent;

said valve body inlet oponing being located opposite said guiding aperture.

3. The compression control device as set forth in claim 1 in which:

h. said valve body has an extension adapted to be fitted into said hole in said engine to establish said communication; said valve body also having a guidincluding a stem fitted to the inner end of said tubular part and extending into said valve body .e xtension;

j. said stem having a closure engageable with a seat formed on said valve body extension to determine said limit and to close said inlet opening;

k. said tubular part having side ports that communicate with said chamber only upon said predetermined movement of said valve member.

4. The compression control device as set forth in claim 3 together with a check valve means at said tubular part operative to determine unidirectional flow through said vent.

5. In a two cycle motorcycle engine having means forming a cylinder and said engine having a hole extending from the cylinder, the combination therewith of a compression control device having a. a valve body attached at said engine hole;

b. a valve member in the body and guided for movement in a path;

c. means forming one limit to the movement of said valve member;

d. spring means urging the valve member to said one limit;

e. an actuator manually operable to move said valve member away from its said one limit;

f. means operable upon a certain amount of movement of said valve member away from its said one limit to add a predeterminedincremental volume to said engine cylinder via said engine hole;

g. means operable only after a predetermined course of movement of said valve member farther away from its said limit than said certain amount to vent said engine cylinder via said engine hole. 

1. In a compression control device for use with a two cycle motorcycle engine having a hole leading to a cylinder: a. a valve body providing a chamber of predetermined volume, said chamber having an inlet opening and a vent; b. means for attaching said valve body to said engine to place said chamber inlet in registry with said engine hole; c. a valve member carried by said valve body and guided for movement in a defined path; d. means forming a limit to the movement of the valve member in one direction in its path in which said valve member interrupts communication between the registered chamber inlet and engine hole; e. spring means urging said valve member toward said limit; f. an actuator manually operable to move said valve member away from said limit a certain amount to establish communication between said engine hole and said chamber; g. means operable between said valve member and said vent to open said vent only after a predetermined movement of said valve member farther away from said one limit than said certain amount whereby, for starting purposes, a definite sealed incremental volume is added to said engine cylinder, and whereby for braking purposes, said engine cylinder is vented.
 2. The compression control device as set forth in claim 1 in which said valve body has a guiding aperture for said valve member opening into said chamber; said valve member including a tubular part and a solid part fitted into the tubular part, the tubular part being guided at said aperture for substantially rectilinear movement and comprising passage means to said vent; said valve body inlet oponing being located opposite said guiding aperture.
 3. The compression control device as set forth in claim 1 in which: h. said valve body has an extension adapted to be fitted into said hole in said engine to establish said communication; said valve body also having a guiding aperture opposite said extension; i. said valve member including a tubular part guided in said aperature and comprising passage means to said vent; said tubular part having an outer end and an inner end, the outer end extending outwardly beyond said aperture, the said valve member also including a stem fitted to the inner end of said tubular part and extending into said valve body extension; j. said stem having a closure engageable with a seat formed on said valve body extension to determine said limit and to close said inlet opening; k. said tubular part having side ports that communicate with said chamber only upon said predetermined movement of said valve member.
 4. The compression control device as set forth in claim 3 together with a check valve means at said tubular part operative to determine unidirectional flow through said vent.
 5. In a two cycle motorcycle engine having means forming a cylinder and said engine having a hole extending from the cylinder, the combination therewith of a compression control device having a. a valve body attached at said engine hole; b. a valve member in the body and guided for movement in a path; c. means forming one limit to the movement of said valve member; d. spring means urging the valve member to said one limit; e. an actuator manually operable to move said valve member away from its said one limit; f. means opeRable upon a certain amount of movement of said valve member away from its said one limit to add a predetermined incremental volume to said engine cylinder via said engine hole; g. means operable only after a predetermined course of movement of said valve member farther away from its said limit than said certain amount to vent said engine cylinder via said engine hole. 